MEXICO CITY (AP) — Police, prosecutors and forensic examiners in the northern Mexico state of Sinaloa all conspired to cover up the killing of an opponent of the ruling-party state governor, using a blood-stained truck found at the crime scene, federal prosecutors said Sunday.

The bombshell statement by federal prosecutors backs up the version of imprisoned drug lord Ismael “El Mayo” Zambada. Zambada claims he was forced aboard an airplane on July 25 by another drug capo who flew them both to the United States and turned them in to U.S. authorities.

Zambada said in a letter in August that Héctor Cuén, an opponent of ruling-party Gov. Ruben Rocha, was murdered on July 25 at the same time and the same ranch where Zambada was kidnapped. Federal prosecutors revealed Sunday that Cuén’s blood was indeed found at the ranch.

Gov. Rocha has not responded publicly to Sunday’s statement by prosecutors, but he has said in the past that Cuén was killed by gunmen in a random botched robbery at a gasoline station miles away later that day, and Sinaloa state prosecutors showed security camera footage of the alleged attack.

But federal prosecutors quickly noted something was wrong with that video: post-mortem records showed Cuén’s body had four gunshot wounds, while only one gunshot can be heard on the security camera footage, and gas station employees said they didn’t hear any.

Cuén's bullet-ridden body could not help solve the riddle, because Sinaloa officials violated all murder investigation rules by allowing the body to be cremated almost immediately.

The gasoline station footage was later proved to be a falsification, but something about the white pickup truck seen in the footage was real: it had the blood of one of Zambada's trusted bodyguards in the cargo bed.

That implied that Sinaloa state police, crime scene investigators and prosecutors either found the bodyguard's corpse in the truck and got rid of the body, or at very least took the blood-stained vehicle from a crime scene to fake a gunpoint robbery at the gas station.

“All of the above confirms the police and prosecution investigation that has confirmed the presumed administrative and criminal responsibilities of Sinaloa police, detectives, forensic examiners and state prosecutors who have been exhaustively investigated regarding their participation in the death of Héctor (Cuén)” the federal Attorney General's Office said in a statement Sunday.

The news appears to complicate further the position of Gov. Rocha, who belongs to President Claudia Sheinbaum’s ruling Morena Party. Sheinbaum has strongly backed Rocha so far. But Rocha has done little or nothing to quell the bloody fighting that broke out between the rival factions of the two Sinaloa drug cartel capos that broke out after July 25.

Instead, Rocha has sought to downplay the gunbattles, killings, kidnappings and cartel roadblocks that have sprung around the state capital, Culiacan. On Thursday, hours before gunmen opened fire on the offices of a local newspaper, Gov. Rocha said “there is nothing to worry about” and “everything is under control.”

Rocha — a close associate of former president Andrés Manuel López Obrador, who left office Sept. 30 — has been implicated in the events of July 25 from the start, though he denies it.

Zambada has said that Joaquín Guzmán López — a leader of a rival cartel faction who he nonetheless trusted — had invited him to the meeting to help iron out the fierce political rivalry between Gov. Rocha and Cuén, who were feuding.

Zambada was famous for eluding capture for decades because of his incredibly tight, loyal and sophisticated personal security apparatus. But he said that on July 25, he left most of his security team behind and entered with only two bodyguards because he expected both Cuén and Gov. Rocha to be present.

The two bodyguards have not been heard from since.

The fact that Zambada would knowingly leave all his security behind to meet with the politicians suggests he viewed such a meeting as credible and feasible. The same goes for the idea that Zambada, as the leader of the oldest wing of the Sinaloa cartel, could act as an arbiter in the state’s political disputes.

Rocha has denied he knew of or attended the meeting where Zambada was abducted, claiming he had borrowed a businessman's private jet to fly to California that day. But while a flight record of that plane exists, Rocha has never shown the immigration documents he would have filed to enter the United States, leading to doubts that he was aboard the plane.

The perceived betrayal of El Mayo has led to fierce fighting between his followers, known as “Mayitos,” and the followers of Guzmán López, who — as one of the sons of imprisoned drug lord Joaquín “El Chapo” Gúzman — was a co-leader of the faction known as the “Chapitos.”